FastSort Manual

Optimizing Sort Performance
FastSort Manual—429834-003
9-6
Using Scratch Files
Table 9-1. How FastSort Chooses Scratch Volumes
What You Specify: How FastSort Responds:
Nothing: no scratch file, no DEFINEs
with scratch attributes, no scratch
volumes, no restrictions on scratch
volumes
Uses volume characteristics to select a scratch
volume. FastSort creates scratch files on this
volume until it is 80 percent full, selects another
scratch volume if necessary, and so on.
A scratch file Uses the file until it becomes full. If the user
manually creates the scratch file and it
becomes full, FastSort tries to increase
MAXEXTENTS and continue using the file. If
overflow scratch files are needed, FastSort
creates them on the current volume until it is 80
percent full. Then FastSort uses volume
characteristics to choose another scratch
volume. FastSort creates scratch files on the
new volume until it is 80 percent full, and so on.
A scratch volume Creates scratch files on the volume until it is
100 percent full. Then FastSort uses volume
characteristics to choose another scratch
volume and creates scratch files on the second
volume until it is 80 percent full, and so on.
A list of scratch volumes Resolves any wild-card characters in the
scratch volumes list and assigns scratch files to
the volumes in a sequential fashion. If
necessary, FastSort creates scratch files on
these volumes until they are 100 percent full.
Then FastSort uses volume characteristics to
choose additional scratch volumes, if needed.
A scratch file or scratch volumes and
restrictions on scratch volumes with
NOSCRATCHON
Uses the scratch file or scratch volumes
specified and does not use the volumes
specified with NOSCRATCHON. If you specify
scratch volumes, FastSort fills them up to 100
percent full.
Only restrictions on scratch volumes with
NOSCRATCHON
Ignores the volumes specified in
NOSCRATCHON and uses characteristics to
select a scratch volume. FastSort creates
scratch files on the volume until it is 80 percent
full. Then FastSort uses volume characteristics
to choose another scratch volume, creates
scratch files on the second volume until it is 80
percent full, and so on.
A scratch file or volume, or a scratch file
and scratch volumes, restrictions on
scratch volumes, a CREATE INDEX
configuration file, and DEFINEs
Uses values in the configuration file. The values
and options specified in the configuration file
override those specified in DEFINEs. FastSort
fills the specified scratch volumes up to 100
percent full.